The present invention relates generally to fuel tanks for vehicles and, more particularly, to a digital signal fuel sensor for a fuel tank of a vehicle.
It is known to provide a fuel tank in a vehicle to hold fuel to be used by an engine of the vehicle. It is also known to provide a fuel sensor in the fuel tank to sense the level of fuel in the fuel tank. Typically, the fuel sensor includes a ceramic card or variable resistor operatively connected to structure of a fuel delivery module and a wiper assembly pivotally connected to the structure for engaging the variable resistor. The wiper assembly has one end connected to a float to rotate the wiper assembly relative to the variable resistor based on a level of fuel in the fuel tank. The wiper assembly has another end with either single or multiple contact loops extending toward the variable resistor and contacts on the contact loops to engage conductive inks on the variable resistor.
Typically, the fuel sensors are analogue devices that measure fuel height or fuel level through a position change by a float arm that is connected to the fuel sensor. The position change is a change in resistive measurement by the fuel sensor to indicate a change in the fuel level. The current fuel sensors suffer from two main disadvantages, which current methods try to balance. Those disadvantages are physical wear and noisy electrical signals. The physical wear occurs when the conductive inks are rough and the loading on the wiper assembly is heavy. Noise occurs when the loading on the wiper assembly is light and a good electrical contact cannot be made. This poor electrical connection between the contacts of the wiper assembly and the ink are the result of an oxidized layer or contaminant build up layer on the ink. This buildup results in a varying circuit resistance and produces unwanted electrical noise.
Therefore, it is desirable to provide a fuel sensor that has a digital switching device. It is also desirable to provide a fuel sensor that incorporates digital switching to eliminate noise. It is further desirable to provide a fuel sensor that changes the ceramic card to incorporate digital switching.
It is, therefore, one object of the present invention to provide a new fuel sensor for a fuel tank.
It is another object of the present invention to provide a digital signal fuel sensor that incorporates a digital switching device into a digital to analogue decoder.
To achieve the foregoing objects, the present invention is a digital signal fuel sensor including a digital sensor and a wiper assembly for rotation relative to the digital sensor. The digital sensor has a plurality of sensing portions having at least one conductive segment thereon forming a fuel level portion. The wiper assembly also includes a plurality of contact arms extending toward the digital sensor for contacting the sensing portions of the digital sensor as the wiper assembly rotates to produce a binary output.
One advantage of the present invention is that a digital signal fuel sensor is provided for a fuel tank of a vehicle, producing a digital binary output to represent the angular deflection of the fuel sensor. Another advantage of the present invention is that the digital signal fuel sensor eliminates noise from the ceramic card and permits optimum contact loading and ink surface for maximum wear. Yet another advantage of the present invention is that the digital signal fuel sensor incorporates digital switching, which is not sensitive to electrical noise as it is represented as a zero (signal low) or a one (signal high), and an electrical signal present in any form with or without noise will be represented as a one (signal high). Still another advantage of the present invention is that the digital signal fuel sensor reduces cost because special rare metal inks are not necessary. A further advantage of the present invention is that the digital signal fuel sensor provides greater resolution and design flexibility. Yet a further advantage of the present invention is that the digital signal fuel sensor reduces vehicle warranty costs by reducing electrical noise and reduced physical wear.
Other objects, features, and advantages of the present invention will be readily appreciated, as the same becomes better understood, after reading the subsequent description taken in conjunction with the accompanying drawings.